What kind of errors do you get with those websites? Do they complain or is data missing? Can you post some links?

Can you attach a screenshot?

• https://support.mozilla.org/en-US/kb/how-do-i-create-screenshot-my-problem
• use a compressed image type like PNG or JPG to save the screenshot

If you use extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) that can block content (Adblock Plus, NoScript, DuckDuckGo PE, Disconnect, Ghostery, Privacy Badger, uBlock Origin), always make sure such extensions do not block content.

• make sure your extensions and filters are updated to the latest version
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

You can check for issues with Enhanced Tracking Protection. Firefox shows a purple shield instead of a gray shield at the left end of the location/address bar in case Enhanced Tracking Protection is blocking content.

• click the shield icon for more detail and possibly disable the protection

You can check the Web Console for relevant-looking messages like about blocked content.

• https://support.mozilla.org/en-US/kb/enhanced-tracking-protection-firefox-desktop
• https://support.mozilla.org/en-US/kb/total-cookie-protection-and-website-breakage-faq
• https://support.mozilla.org/en-US/kb/trackers-and-scripts-firefox-blocks-enhanced-track

I want to make it clear that this is not a criticism of Firefox.

I want to know what possible consequences I might expect or be made aware of, in general, in terms of sites in Firefox where things that should work don't, but sometimes do work on a Chromium based browser.

Occasional nuisances that I want to treat sensibly to not make things worse by setting security to extreme levels.

I just want to know the pros and cons. What I might expect in some sensitive cases.

The DNT and GPC options in your screenshot do nothing in Firefox, but merely send a signal to the website by adding DNT:1 and Sec-GPC:1 via the HTTP request headers, it is up to the website to decide whether to take action. The should normally not be causing issues, unlike when ETP or TCP or an extension is blocking (essential) content.

• https://support.mozilla.org/en-US/kb/how-do-i-turn-do-not-track-feature
• https://support.mozilla.org/en-US/kb/global-privacy-control

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Use Windows snipping tool to provide a full browser screenshot similar to mine. Site search results works for me. see screenshot

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The DNT and GPC options in your screenshot do nothing in Firefox, but merely send a signal to the website by adding DNT:1 and Sec-GPC:1 via the HTTP request headers, it is up to the website to decide whether to take action. The should normally not be causing issues, unlike when ETP or TCP or an extension is blocking (essential) content.

• https://support.mozilla.org/en-US/kb/how-do-i-turn-do-not-track-feature
• https://support.mozilla.org/en-US/kb/global-privacy-control

Would you mind checking this out problematic site. A supermarket. link text

Ublock disabled, cookies enabled. Search results on a loop, never completed. The next image is from Chrome with no problems

https://i.postimg.cc/QCL5WmhG/alb.jpg

The next image is from Chrome with no problems

https://i.postimg.cc/QdcgLcXR/alb2.jpg

I still don't care about cookies is the root of the behavior. It makes sense now

I'm not criticizing the addon for doing it's job. It has a whitelist, but I will let the developers know. At times that grocery site has been shady, i.e. regardless of where you live, If you don't login there, by default you get a weekly ad from their corporate location in Idaho. They know about that, but they are big on collecting data. I don't see a lot of these elsewhere https://i.postimg.cc/HkvKvXPK/alb3.png

My only problem is, if you want to use the app, how do you know when it it's causing a conflict? But I guess that's the price of admission.